Because our bodies have a set weight that they like to maintain, yo-yo dieting really interferes with the process of weight loss and weight gain.

Avoid yo-yo dieting. Make lifelong changes. All yo-yo dieting does is reinforce the feast and famine response. Your body will learn to store excess calories as fat even more efficiently than before. Every study that has been done on people who lost weight, then regained it, shows that they lost fat and muscle initially, but gained back mostly fat (not muscle). Our bodies are very smart and protective. Don’t let this happen to you. Our bodies like to protect themselves.

If you look at the above chart, during a period of semistarvation, patients lost a lot of fat (the green line) as well as some lean mass (the blue line).

Once they started refeeding and gained weight back, they gained more fat than lean body mass. The green line comes back higher than the blue line. So while they gained back both fat and muscle, they gained back a lot more fat.

When they were being overfed (hyperphagia), most of that weight gain was fat.

Our bodies can become used to this cycle and become very efficient at storing fat if we keep yo-yo dieting, losing weight, then gaining it back. Losing weight, then gaining it back. Don't let this happen to you!